End-cell switch.



M7 I Wg-W J. W. ACHARD.

END CELL SWITCH. .wPLlcATloN mfp Nov. 2. 191|.

1 ,2O 1 ,4 1 8 Patented Oct. 17, 1.916.

- fication.

.'roHN W.,y AcHAnD. or PHILADELPHIA, PENNSYLVANIA.

vEND-onu. SWITCH. l

Specification of Letters Patent. j Patented Oct, 17, 1916,

` Application led November 2, 1911. Serial No. 658,245.

To all whom t may concern l Be it known that I, JOHN W. AoHARD, a citizen of the United States, and a resident of Philadelphia, county of Philadelphia, State of Pennsylvania, have invented certain new and useful Improvements in End-Cell Switches, of which the following is a speci- My invention relates to switches in which a movable contacting member coperates with a series of contacts connected to the intermediate points in a series of storage battery cells, and especially'to such switches in which auxiliary resistances are employed on either side of the contacts to prevent opening-the circuit when the movable member travels from one contact to the next, and at the same time to prevent an excessive flow of current when `the movable member is located b tween two contacts. Auxiliary contact bloc s of comparatively high resistance have been used for this purpose made of'material such as graphite or carbon. In some cases, however, it is found desirable that the resistance of such auxiliary contacts shall increase rapidly as the moving mem-A respect. In order to obtain this result, in-

accordance with my invention, I provide a plurality of laterally arranged blocks of comparatively high resistance, and of such material as will also offer an appreciable resistance across the contact surfaces between adjacent blocks. I utilize this Contact resistance to secure the desired results, and also provide means for adjusting Ithe value of this resistance.

My invention will be more clearly understood by 'reference to the following description taken in connection with the accompanying drawings in whichl Figure 1, is a diagrammatic view of an end cell switch embodying features of my invention, with its circuit connections. Fig. 2, is a section of one of the contacts along the line A A of Fig. l, drawn to an enlargedy scale. Fig. 3, is a plan view of one of the contacts, and Fig. 4, is a section taken alon the-line X X of Fig..3. v

Referring'to Fig. 1, B is a storage battery connected at one terminal to conductor` 1 of the consumption circuit 1 7, while the other terminal, and several intermediate pointsvof the battery are connected respectively to contacts 2, 3, 4, 5 and 6 of an end cell switch. A traveling brush D operated' by means of a screw E, and a crank F connects lany one of the several contacts to the continuous conducting bar C, which is connected to the opposite conductor 7 of the consumption circuit. rower than the space between two main contacts, such as 4 and 5, but these contacts are provided with laterally disposed auxiliary contact blocks 11, which partially bridge the gap between adjacent contacts, and prevent the circuit from being opened as the brush moves from one contact to the next. These auxiliary contacts 11 consist of a series of blocks which may be of carbon or graphite. scale in the sectional view given in Fig. 2. Referring to thisiigure, the main contact, which may be made of conducting metal,

`such as copper, is forked to receive a block of high resistance material, such as carbon, this latter being shown at 9. The upper and lower portions of the lfork are shown 1n section at 8 and 8b. The bolts 10 serve to clamp the upper and lower members of the fork in good contact with the carbon block 9. The block 9 extends oneither side of the fork, being notched to receive the fork so l'that thel upper and lower surfaces of the fork, and the carbon block, are flush. Laterally attached to the carbon block 9, by

means of bolts 12, are'shown auxiliary car-l bon blocks or laminations 11, whosefupper and lower surfaces are alsoflush with the surface of the main block 9, and the fork 8 and 8b. A metallic plate 215 is shown under the nuts of the bolts 12V to distribute lthe pressure, and thebolts are themselves insu- -lated from the laminations 11 by means of The brush D is nar-- They are shown on a larger' insulating sleeves 13, and from the metallic plate 15 by means of insulating Washers 14.

Referring 'again to Fig. 1 it'will be seen Y the laminations themselves are successivelythrown into circuit, thus increasing the circuit'resistance rapidly with a small travel of the brush. Similarly as the brush approaches one of the contacts, the resistance, which is high at first, is rapidly reduced as the contact resistances between the surfaces of the carbon blocks are cut out of circuit. The resistances between these surfaces vary with the pressure, and these resistances may, therefore, be adjusted by adjusting the pressure produced between the contact surfaces by the bolts 12. An adjustment may also bel effected by means of longitudinal grooves or recesses 16 which reduce the area of contact. By adjusting the width of these grooves the contact resistance may be adjusted as desired.

Fig. 3 is a plan view of one of the contacts showing the details on a larger scale, the same reference numbers being used to designate corresponding parts.

Fig.4 4 is a sectional view along the line X X of Fig. 3, showing more clearly the construction of the fork of the main contact.

Having described my invention, what I claim. and desire to secure by Letters'Pat- I contact with each other, and whereof one is in permanent contact with the main contact, substantially as described.

2. A switch contact having in combination a main contact and a series of contact resistance laminations in permanent contact With each other, and whereof one is in permanent contact with the main contact, and4 means for adjusting the contact pressure of said laminations.

In .testimony whereof I have hereunto signed my name in the presence of two wit- 

